/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.sdk.io.gcp.bigquery;



import com.google.api.services.bigquery.model.TableRow;

import com.bff.gaia.unified.sdk.coders.Coder;

import com.bff.gaia.unified.sdk.coders.Coder.Context;

import com.bff.gaia.unified.sdk.io.FileSystems;

import com.bff.gaia.unified.sdk.io.fs.ResourceId;

import com.bff.gaia.unified.sdk.util.MimeTypes;

import com.bff.gaia.unified.vendor.guava.com.google.common.io.CountingOutputStream;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;



import java.io.IOException;

import java.nio.channels.Channels;

import java.nio.channels.WritableByteChannel;

import java.nio.charset.StandardCharsets;

import java.util.UUID;



import static com.bff.gaia.unified.vendor.guava.com.google.common.base.Preconditions.checkState;



/** Writes {@link TableRow} objects out to a file. Used when doing batch load jobs into BigQuery. */

class TableRowWriter implements AutoCloseable {

  private static final Logger LOG = LoggerFactory.getLogger(TableRowWriter.class);



  private static final Coder<TableRow> CODER = TableRowJsonCoder.of();

  private static final byte[] NEWLINE = "\n".getBytes(StandardCharsets.UTF_8);

  private ResourceId resourceId;

  private WritableByteChannel channel;

  private CountingOutputStream out;



  private boolean isClosed = false;



  static final class Result {

    final ResourceId resourceId;

    final long byteSize;



    public Result(ResourceId resourceId, long byteSize) {

      this.resourceId = resourceId;

      this.byteSize = byteSize;

    }

  }



  TableRowWriter(String basename) throws Exception {

    String uId = UUID.randomUUID().toString();

    resourceId = FileSystems.matchNewResource(basename + uId, false);

    LOG.info("Opening TableRowWriter to {}.", resourceId);

    channel = FileSystems.create(resourceId, MimeTypes.TEXT);

    out = new CountingOutputStream(Channels.newOutputStream(channel));

  }



  void write(TableRow value) throws Exception {

    CODER.encode(value, out, Context.OUTER);

    out.write(NEWLINE);

  }



  long getByteSize() {

    return out.getCount();

  }



  @Override

  public void close() throws IOException {

    checkState(!isClosed, "Already closed");

    isClosed = true;

    channel.close();

  }



  Result getResult() {

    checkState(isClosed, "Not yet closed");

    return new Result(resourceId, out.getCount());

  }

}